The former Arsenal star converted from the spot to make it 3-0 after Delhi goalkeeper Kristof Van Hout had brought down Tolgay Ozbey following Youness Bengelloun's double.
Ozbey then put the game beyond any doubt, with Gustavo Marmentini's spot-kick for Delhi serving as nothing more than a consolation in a defeat that saw the capital club leapfrogged by Goa.
Goals were at a premium elsewhere in the league as the other three games in the eighth round of fixtures finished goalless.
The top-of-the-table clash between Atletico de Kolkata and Chennaiyin appeared set to be the most exciting match of the round, but the early pacesetters cancelled each other out in a 0-0 draw that will be best remembered for the floodlights at Salt Lake Stadium going off in the 36th minute.
Pune City failed to take advantage of that result, missing the chance to make it a three-way tie at the summit as they were frustrated by NorthEast United and left to settle for a point from their trip to Guwahati.
Kerala Blasters' meeting with Mumbai City also produced a stalemate, although the visitors were unfortunate not to break the deadlock when midfielder Thiago Ribeiro hit the post in the second half.
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